In triangle DEFDEFDEF, ED=5cmED = 5\text{cm}ED=5cm and EF=6cmEF = 6\text{cm}EF=6cm. Given that sin(∠DEF)=23\displaystyle \sin(\angle DEF) = \frac{2}{3}sin(∠DEF)=32 and ∠DEF \angle DEF\,∠DEF is acute.
Find the exact value of cos(∠DEF)\cos(\angle DEF)cos(∠DEF)
Find the length of DFDFDF.
Find ∠EFD\angle EFD∠EFD.
Practise AQA A Level Maths 1.8 E: Trigonometry with exam-style questions for A Level Maths. 239 questions covering 1.8.1 Trigonometric definitions, rules and radians, 1.8.2 Small angle approximations (A-level only), 1.8.3 Trigonometric functions and exact values, 1.8.4 Reciprocal and inverse trigonometric functions (A-level only), 1.8.5 Trigonometric identities, 1.8.6 Compound and double angle formulae (A-level only), 1.8.7 Solving trigonometric equations, 1.8.8 Proofs with trigonometric identities, and 1.8.9 Trigonometry in context, matched to the AQA A Level Maths (7357) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
